CN108213461B

CN108213461B - Preparation method of nano-grade noble metal material

Info

Publication number: CN108213461B
Application number: CN201711321425.2A
Authority: CN
Inventors: 傅强; 胡劲; 段云彪; 翟又文; 刘璇; 王亚飞
Original assignee: Kunming University of Science and Technology
Current assignee: Kunming University of Science and Technology
Priority date: 2017-12-12
Filing date: 2017-12-12
Publication date: 2021-07-16
Anticipated expiration: 2037-12-12
Also published as: CN108213461A

Abstract

The invention relates to a preparation method of a nano-scale noble metal material, belonging to the field of material preparation. The invention uses fiber to make blank, immerges the blank into noble metal precursor solution, to make noble metal ion distribute on fiber frame of fiber under capillary force, then drying and sintering, the noble metal precursor on fiber frame generates decomposition reaction in sintering process, at the same time, the fiber blank is burned and gasified under high temperature, to obtain fine noble metal particles with fine crystal grain, uniform size and large specific surface area.

Description

Preparation method of nano-grade noble metal material

Technical Field

The invention relates to a preparation method of a nano-scale noble metal material, belonging to the field of material preparation.

Background

The particle size range of the fine noble metal particles is 100nm-10 mu m, and the fine noble metal particles have high specific area and high reaction activity due to quantum size effect and unique morphological characteristics thereof, show special electrical, optical, magnetic and chemical properties different from those of block materials, and are widely applied to the fields of sensors, anticancer drugs, photoelectron materials, ultrahigh-density magnetic storage materials, tunneling magneto-resistance devices, magnetic fluid materials, catalyst materials, electro-catalyst materials and the like.

The traditional preparation method of the fine precious metal particles mainly adopts a liquid phase method, and the principle is as follows: the method is characterized by taking noble metal salts as precursors, and reducing noble metal ions into noble metal simple substance metal by using a proper reducing agent in different solvent systems. The reduction process is accompanied with the nucleation, growth and agglomeration process of the noble metal crystal grains. In the nucleation process, noble metal ions are converted to an atomic state, and a plurality of atoms form atomic clusters in the collision process, so that larger-size atomic cluster aggregation is formed, but the atomic cluster aggregation reaches the critical nucleation size, namely, crystal nuclei are formed, and the crystal nuclei grow and aggregate to obtain noble metal particles.

Disclosure of Invention

The invention aims to provide a preparation method of a nano-scale noble metal material, which comprises the following steps: preparing a blank body by using fibers, immersing the blank body into a noble metal precursor solution to ensure that noble metal ions are uniformly distributed on a fiber framework of the fibers under the action of capillary force, and then drying and sintering; during the sintering process, the noble metal precursor on the fiber skeleton is decomposed and gasified at high temperature to obtain fine noble metal particles with fine crystal grains, homogeneous size and great specific surface area.

The noble metal precursor is a noble metal compound, a noble metal salt or a noble metal organic compound, wherein the thermal decomposition temperature of the noble metal precursor is below 1000 ℃, and the decomposition product contains a noble metal simple substance, wherein the noble metal simple substance is any one of platinum, ruthenium, rhodium, palladium, iridium and gold; such as chloroplatinic acid, ammonium tetrachloropalladate, bis (triphenylphosphine) palladium chloride 99% -Pd, ruthenium hexammine dichloride, rhodium nitrate, rhodium acetylacetonate bis (ethylene) and the like.

Preferably, the specific process for preparing the fiber into the blank body comprises the following steps: soaking the purified fiber with 5% -15% hydrochloric acid for 30 minutes, washing until the pH is =7, drying, treating with mixed acid of hydrofluoric acid and hydrochloric acid for 15-30 minutes (the mass percent concentration of the hydrofluoric acid in the mixed acid is 5% and the mass percent concentration of the hydrochloric acid is 10%), washing off metal ions in the fiber, washing with distilled water, and drying to obtain a fiber blank (the ignition residue is less than 0.01% after ignition).

Preferably, the concentration of the noble metal precursor solution is 0.05-1g/L of metal content, and the soaking time of the blank is 20-30 minutes.

Preferably, the sintering atmosphere in the present invention is air, vacuum, inert atmosphere or reducing atmosphere, and the sintering temperature is a temperature at which the sintered precursor is completely decomposed.

The fiber blank of the invention is not limited, and all fibers which can uniformly adsorb the noble metal precursor solution and do not have chemical reaction with the noble metal precursor can be used as the fiber blank, such as plant fibers, polymer fibers, animal protein fibers and the like.

All percentages in the present invention are mass percentages, not specifically stated.

The invention has the beneficial effects that:

(1) by controlling the heating temperature and the process conditions, the invention can obtain fine noble metal particles with 2nm-100 mu m of fine crystal grains, uniform size and larger specific surface area; the obtained fine noble metal particles have high purity, strong controllability of crystallite grain diameter, narrow grain size distribution, good uniform dispersity and large specific surface area.

(2) The method has the advantages of low cost, high yield, no use of reducing agent and dispersing agent, short process flow, simple and controllable process and high yield up to 100 percent; compared with the traditional liquid reduction method, the whole preparation process is green and environment-friendly, and has no pollution problem.

Drawings

FIG. 1 is an SEM spectrum of iridium particles in example 1;

FIG. 2 is an SEM spectrum of ruthenium particles in example 2;

fig. 3 is an SEM image of the platinum particles in example 3.

Detailed Description

The invention will be further described with reference to the following examples and the accompanying drawings, but the invention is not limited to the scope described below.

Example 1

Selecting primary raw cotton refined cotton as a fiber blank raw material, pulping the raw material in a long fiber free state, soaking and purifying the fiber by using 10% hydrochloric acid for 30 minutes, washing the fiber until the pH is =7, drying the fiber, treating the fiber for 15 minutes by using mixed acid of 5% hydrofluoric acid and 10% hydrochloric acid, washing the fiber by using distilled water, and drying the washed fiber to prepare a fiber blank; the burning residue of the fiber blank body after burning is less than 0.009%.

Dissolving acetylacetone iridium in water to prepare 150ml of aqueous solution with iridium ion concentration of 0.05mol/L, placing the aqueous solution in a watch glass, placing the prepared fiber blank in an acetylacetone iridium solution system for 1.5 minutes to enable the fiber blank to fully absorb the acetylacetone iridium solution, and taking out the fiber blank to naturally dry at room temperature; placing the dried fiber blank in a sintering furnace, setting the sintering temperature to be 500 ℃, preserving the heat for 1 hour in the atmosphere, and cooling along with the furnace; the sintered product is taken out to obtain the metallic iridium fine particles, the SEM spectrum of which is shown in figure 1, and the iridium particles prepared by the method are porous structures with the pore size of 100-250 nM.

Example 2

Selecting mulberry silk as a fiber blank raw material, soaking and degreasing the mulberry silk for 24 hours by using acetone, drying the mulberry silk, treating the mulberry silk for 15 minutes by using 5 percent hydrochloric acid, washing the mulberry silk by using distilled water, and drying the mulberry silk to prepare a fiber blank; the burning residue of the fiber blank body after burning is less than 0.03 percent;

dissolving ruthenium trichloride in water to prepare 150ml of aqueous solution with the ruthenium ion concentration of 0.05mol/L, placing the aqueous solution in a watch glass, placing the prepared fiber blank in a ruthenium trichloride solution system, placing the watch glass in a vacuum air extractor bell jar, starting a vacuum pump, pumping the vacuum degree in the vacuum bell jar to 0.08MP, keeping the vacuum degree for 30 minutes, fully soaking the ruthenium trichloride solution in porous fiber gaps in the fiber blank, and taking out the fiber blank to naturally dry at room temperature. And (3) placing the dried fiber blank in a sintering furnace, setting the sintering temperature to be 550 ℃, introducing hydrogen, preserving the heat for 1 hour, and cooling along with the furnace. And taking out the sintered product, adding an ethanol solution, performing ultrasonic vibration for 10 minutes, introducing nitrogen, separating residual incompletely reacted carbon from the ruthenium fine particles by floating on the liquid surface, filtering and drying to obtain the ruthenium fine particles, wherein an SEM (scanning electron microscope) spectrum of the ruthenium fine particles is shown in figure 2, the metal ruthenium fine particles are of a three-dimensional porous framework structure, the framework size is 700-500 nM, and 100-200 nM holes are distributed on the framework.

Example 3

6500 metric count flax fiber is selected as a fiber blank raw material, the fiber blank is pulped by long fiber in a free state, the purified fiber is soaked in 10% hydrochloric acid for 30 minutes, the pH =7 after washing, the fiber blank is treated by mixed acid of 8% hydrofluoric acid and 15% hydrochloric acid for 15 minutes after drying, and then the fiber blank is prepared by washing the fiber blank with distilled water until the pH =7 and drying. The burning residue of the fiber blank is less than 0.01 percent after burning.

Dissolving chloroplatinic acid in water to prepare 150ml of water solution with the platinum ion concentration of 0.1mol/L, placing the water solution in a watch glass, placing the prepared fiber blank in a chloroplatinic acid solution system for 1 minute to enable the fiber blank to fully absorb the chloroplatinic acid solution, taking out the fiber blank, and naturally drying at room temperature. Placing the dried fiber blank in a sintering furnace, setting the sintering temperature to 700 ℃, keeping the temperature of the atmosphere for 1.5 hours, and cooling along with the furnace; the sintered product is taken out to obtain the metal platinum fine particles, wherein the SE spectrum BSE spectrum of the metal platinum fine particles is shown in fig. 3, wherein (a) is a SE (secondary electron) spectrum, and (b) is a BSE (back scattered electron) spectrum, and the SE spectrum of the metal platinum fine particles and the BSE spectrum of the metal platinum fine particles in the (a) and (b) have the same stereo morphology.

Claims

1. A preparation method of a nano-scale noble metal material is characterized by comprising the following steps: preparing a blank body by using fibers, immersing the blank body into a noble metal precursor solution to ensure that noble metal ions are uniformly distributed on a fiber framework of the fibers under the action of capillary force, and then drying and sintering; in the sintering process, the noble metal precursor on the fiber framework is subjected to decomposition reaction, and the fiber blank is combusted and gasified at high temperature, so that fine noble metal particles are obtained;

the specific process for preparing the blank from the fibers comprises the following steps: soaking the purified fiber with 5-15% hydrochloric acid for 30 minutes, washing until the pH is =7, drying, treating with mixed acid of hydrofluoric acid and hydrochloric acid for 15-30 minutes, simultaneously washing off metal ions in the fiber, washing with distilled water, and drying to obtain a fiber blank;

the concentration of the noble metal precursor solution is 0.05-1g/L of metal content, and the soaking time of the green body is 20-30 minutes.

2. The method for preparing a nanoscale noble metal material according to claim 1, characterized in that: the noble metal precursor is a noble metal compound, a noble metal salt or a noble metal organic compound, wherein the thermal decomposition temperature of the noble metal precursor is below 1000 ℃, and the decomposition product contains a noble metal simple substance.

3. The method for preparing a nanoscale noble metal material according to claim 1, characterized in that: the noble metal is any one of platinum, ruthenium, rhodium, palladium, iridium and gold.